US4480449A - Automatic liquid level control for automatic washers - Google Patents

Abstract

An automatic liquid level control is provided for an automatic washing machine which measures the volume of liquid required to be added to the tub increase the liquid level in the tub by a predetermined increment. The measured amount is compared to a reference amount corresponding to an empty tub. When the measured amount equals the reference amount, the clothes in the washer will be covered and the control terminates introduction of the liquid into the tub and continues with the remainder of the washing cycle.

Description

This is a division, of application Ser. No. 272,677, filed June 11, 1981, now U.S. Pat. No. 4,428,088 issued on Jan. 3, 1984.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a washing machine having an automatic liquid level control, and more particularly to a washing machine wherein the correct amount of washing fluid is selected for the requirements of a given load of clothes, automatically and with no pre-selection by an operator.

2. Description of the Prior Art

Various means have been provided for automatically controlling the liquid level in a washing machine. U.S. Pat. No. 3,086,836 discloses an automatic liquid level control wherein a given volume of liquid is added to the clothes load, the volume not absorbed by the clothes load is measured, and that measurement is utilized to determine the additional volume of liquid to be added to obtain the proper total amount of liquid.

U.S. Pat. No. 3,498,090 utilizes a control system for use in an automatic washer to automatically control the quantity of liquid added to the machine's tub during the wash and rinse operations by using a torque signal generated in the machine by action of the agitator.

U.S. Pat. No. 3,478,374 provides for an automatic liquid level control in an automatic washing machine which involves employing a sensing zone in proximity to the axis of the agitator, applying a reduced pressure at the sensing zone, and then introducing additional amounts of liquid into the machine when the liquid has been depleted from the sensing zone as a result of an excessive amount of wash fabric being present in comparison to the amount of washing liquid.

U.S. Pat. No. 3,478,373 provides an automatic liquid level control which responds to the flow of liquid in a predetermined flow path to sense when the proper amount of washing fluid is present in the tub of the washer.

SUMMARY OF THE INVENTION

The present invention operates on the principle that for any given washer and any given wash load there is a measurable quantity of water that will adequately wash that load in that washer. In order to measure the quantity of water needed, there is first established a relationship between the volume of water added to an empty washer to effect equal incremental changes in the depth or level of the wash bath within the wash container. Then the volume depth change relationship is measured during the washer fill process with a wash load in the washer.

The volume-depth relationship for an empty washer may be looked upon as a constant because for each fill the relationship repeats itself over the range of possible wash depths.

However, with a wash load in the washer, the relationship varies because the load displaces some of the incoming fill water, resulting in a smaller volume of water providing the incremental depth changes.

As the depth of the wash bath is increased the wash load becomes increasingly saturated and/or floats. If more water is added after the load is saturated or is floating, there is no additional displacement resulting from the wash load and the volume-depth relationship will coincide with the empty washer relationship.

Even if the load does not totally saturate or float, the volume-depth relationship approaches that of an empty washer.

By comparing the variable volume-depth relationship occuring during the fill period of a washer containing a wash load, with the fixed or constant volume-depth relationship for an empty washer, a wash bath depth can be selected which is adequate to wash the load in that washer.

In accordance with the present invention an automatic liquid level control for an automatic washer is provided wherein the volume of liquid required to be added to a tub charged with clothes to be washed to result in a given incremental increase in the liquid level within the tub is compared with a predetermined value related to the volume of liquid required to be added to the tub to increase the liquid level by the given increment in an uncharged tub.

When there are clothes present in the tub, there will be a lesser volume of liquid required to raise the level of liquid in the tub by the given increment because the clothes occupy part of the volume within the tub which would have been filled with the liquid. When the actual liquid volume added for each additional incremental increase in the liquid level bears an appropriate predetermined relationship to the predetermined value, then a sufficient amount of liquid will have been added to the tub to properly perform the washing functions of the machine.

A flow sensor is used to determine the volume of liquid added during each incremental increase in the liquid level within the tub and a level sensor is utilized to provide a level increment signal. Both of these signals are directed to a microprocessor which compares the values by means of appropriate circuitry to the values which have been experimentally predetermined. When the microprocessor determines that the level of liquid in the tub has reached a sufficient depth for proper washing it sends appropriate signals to the inlet valves to turn off the inflow of liquid and then continues with the remainder of the programmed washing cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a washing machine embodying the present invention partially cut away to show the interior mechanism thereof.

FIG. 2 is an enlarged side sectional view of the flow sensor utilized in the machine of FIG. 1 in connection with the present invention.

FIG. 3 is a sectional view of the flow sensor taken generally along the lines III--III of FIG. 2.

FIG. 4 is a schematic circuit diagram utilized in the present invention.

FIG. 5 is a flow chart illustrating operation of an automatic liquid level control process.

FIG. 6 is a graph showing the experimentally predetermined values for flow pulse counts per level of increment versus liquid level increments above a minimum and the standard against which the microprocessor compares the readings obtained from the flow sensor and the level sensor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Alaundry appliance 10 comprising an automatic clothes washer embodying the principles of the present invention is depicted in FIG. 1. The washer is comprised of acabinet 12 having atop 14 with anopenable lid 16 and aconsole 18 havingpresettable controls 20 thereon of the type wherein an operator may pre-select a program of automatic washing, rinsing and centrifuging steps in a laundering process. Thelid 16 in thetop 14 of thecabinet 12 permits access into the top of atub 22 housed within the cabinet. Enclosed and supported within thetub 22 is a clothes container orspin basket 24 within which is oscillatably mounted anagitator 26.

Below thetub 22 but within thecabinet 12 there is provided anelectrical motor 28 which oscillatably drives theagitator 26 through atransmission 30. Themotor 28 also drives apump 32.

Alevel sensor 34 is shown in phantom in FIG. 1 and can be similar to the pressure sensitive device described in U.S. Pat. No. 3,086,836. Thelevel sensor 34 is used to determine the incremental changes in the depth of liquid within thetub 22 during the filling portion of the wash cycle. A water inlet including aflow sensor 36 is shown in phantom in FIG. 1 beneath thetop 14 of thewasher 10. Control circuitry means 38 for sequencing the automatic washer through a plurality of washing, rinsing and centrifuging operations is located within theconsole 18.

Theflow sensor 36 is shown in greater detail in FIGS. 2 and 3 where it is seen that the flow sensor is comprised of apaddle wheel 40 having radially extendingpaddle arms 42 withflat blade portions 44 which extend into the incoming flow path of a filling liquid entering thebasket 24 through the water inlet as shown byarrows 46. Thepaddle wheel 40 is mounted on arotatable axle 48 which is journalled withinsleeve bearings 50. Adisk 52 is secured to an end of theaxle 48 for rotation therewith. In order that the number of revolutions of thepaddle wheel 40 can be counted, thedisk 52 is provided with a plurality ofopenings 54 therethrough and a lightemitting diode counter 56 is positioned in alignment relative to theholes 54. In this manner, the volume of liquid entering through the liquid inlet can be accurately determined.

The volume of liquid entering the tub is measured and compared with an experimentally predetermined volume required to raise the level of liquid within an empty tub a specific incremental amount from that particular level in the tub. The predetermined value varies between washer models depending on the tub and agitator configurations and within each model it varies depending on the level of liquid in the tub.

A sample experimentally derivedcurve 57 is shown in FIG. 6 which is a graph showing the number of flow pulse counts required to change the liquid level equal increments for each increment level above a minimum level in a tub with no clothes in it. If the level of the liquid within the tub is below the top of the clothes load within the tub, the clothes will displace some of the volume normally occupied by liquid when there are no clothes in the tub. Bulky items displace the liquid by their weight and their volume, whereas nonbulky items displace the liquid primarily by their weight. A flow pulse count reading below the number on the experimentally determined curve would mean that the liquid level in the tub has moved from one level increment to the next with less liquid added than if the tub had had no clothes in it. This is an indication that there are still clothes displacing some of the liquid being added. When enough liquid has been added so that none of the clothes are displacing liquid being added to the tub, then the clothes by their weight and volume are displacing all the liquid they can displace. Now, the additional volume of liquid required to increase the liquid level increment by one level should be the same as the experimentally determined value for a tub at the same increment level with no clothes in the tub.

In order to determine whether the required amount of liquid has been added to the tub for the various level increments above the minimum level, asecond curve 59 is provided which represents reference values that themicrocomputer 72 utilizes in determining the appropriate flow pulse counts required for the various level increments as will be described more fully hereinafter.

In FIG. 4 there is shown a portion of the control circuitry means 38 which is utilized for the automatic liquid level control. Atransformer 58 in combination with a diode bridge orfull wave rectifier 60 converts normal 120 volt/60 cycle household current into the required DC voltage to be utilized in the circuitry. The current flows alongline 61 through avoltage regulator 62 which provides for a constant voltage to be utilized in the circuitry.Capacitors 63 are provided to remove voltage spikes inline 61.

Current is supplied to theflow sensor 36 alonglines 64 and 65 and throughresistors 66. A square wave signal output from theflow sensor 36 is directed alongline 67 through aresistor 68 to anamplifier 69 where the signal output of theflow sensor 36 is amplified prior to being directed alongline 70 to amicrocomputer 72.

Current is supplied to thelevel sensor 34 alonglines 64, 73 and 74. An analog output signal from thelevel sensor 34 is directed alongline 75 through an analog todigital converter 76 where the analog signal is changed to a digital signal. The digital signal is directed to themicrocomputer 72 along line 78.Voltage divider circuitry 80 is provided to supply reference voltages for comparison by themicrocomputer 72 with the output from thelevel sensor 34 and theflow sensor 36.

Areset switch 82, being the start switch for the automatic liquid level control, supplies a reset current fromline 64 alongline 83 to themicrocomputer 72. Apreset capacitor 84 insures that when power is initially supplied the microcomputer begins the program at the beginning and anRC circuit 86 provides the microcomputer clock frequency.

Output signals from themicrocomputer 72 are directed alonglines 88 and 90 to adriver amplifier 92 which is used to controlrelays 94 and 96 which operate inlet water valves 98.

FIG. 5 illustrates the operation of the apparatus of the present invention during an automatic cycle of operation. FIG. 5 is in a functional block diagram form, with the various blocks indicating steps performed in sequence during the performance of the method of the present invention, and also indicating the structure which is employed during the operation of the washing machine. Although a preferred embodiment of the present invention employs a controller for the performance of the liquid level controlling program, the present invention also contemplates an organization in which each of the blocks illustrated in FIG. 5 corresponds to an individual control unit. Control of the operation is passed from control unit to control unit, to execute the program in its proper sequence. The operation proceeds by a sequence of steps.

The first step in the performance of the automatic operation of the liquid level control is by control unit 100 which turns on or energizes thelevel sensor 34. Control then passes to the unit 102 which opens water valves 98 causing liquid to flow into thetub 22. Control is next passed tounit 104 which reads the liquid level within thetub 22 by means of the signal supplied by thelevel sensor 34. Control passes to aunit 106 which compares the liquid level reading made byunit 104 with a preset minimum liquid level.

If the liquid level is not equal to the minimum level, control is returned tounit 104 so that a new liquid level reading may be taken. This sequence of reading and comparing the liquid level with the minimum level continues until the liquid level equals the preselected minimum level. Whenunit 106 determines that this has occurred, control is passed tounit 108 which stores the liquid level reading fromunit 104 in a memory storage device as level L.

Control is then passed tounit 116 which inspects the output from thelevel sensor 34 to determine if the current liquid level within thetub 22 is equal to a preselected increment above the level stored byunit 108.

Ifunit 116 determines that the liquid level has not yet reached the desired increased level, then control is passed tounit 118 which counts the flow pulse signals from theflow sensor 36. Control is returned tounit 116 which again inspects the output signal from thelevel sensor 34 to determine if the incremental level has been reached. This sequence of checking the level and counting the pulses continues untilunit 116 determines that the liquid level in thetub 22 has increased by one increment.

When this is sensed, control passes tounit 120 which stores the pulse count fromunit 118 in a memory register. In the preferred embodiment of the invention only four pulse count storage registers are utilized and after four counts have been stored, the earliest count stored is dropped and a new count is placed in that register byunit 120.

Control is passed tounit 122 which determines if there have been four pulse count storage procedures byunit 120. If there have not, control is passed tounit 126 which increments the liquid level value L which was first stored byunit 108 and then control is passed tounit 128 which resets the flow pulse count to zero. Control then passes tounit 116 for an iteration of the process untilunit 122 determines that there have been at least four pulse counts stored byunit 120.

Whenunit 122 has made this determination, control is passed tounit 124 which averages the last four flow pulse counts which have been stored in registers byunit 120. Control then passes tounit 130 which compares the average flow pulse count determined byunit 124 with the predetermined preferred liquid volume rate at level L as shown bycurve 59. Ifunit 130 determines that the average flow pulse count fromunit 124 is less than or equal to the preferred count at the stored level, then control is passed tounit 132 which inspects the liquid level L to determine if the current liquid level in the tub is equal to the maximum level allowed.

If the current stored level is below the maximum level, control is passed tounit 126 for iteration of the steps outlined above. Ifunit 132 determines that the current liquid level is equal to the maximum level allowed in thetub 22 then control is passed tounit 134 which deactivates the water valves 98 to terminate the introduction of liquid into thetub 22.

Ifunit 130 determines that the average flow pulse count fromunit 124 is greater than the preferred pulse count at the current stored level, the control is passed tounit 110 which stores the average pulse count and control passes tounit 136 which determines if each of the last four pulse count averages stored byunit 110 have been greater than the preferred pulse count as indicated bycurve 59. Ifunit 136 determines that they have not, then control is passed tounit 132 to resume the process outlined above. However, ifunit 136 determines that each of the last four pulse count averages have been greater than the preferred pulse count then control is passed tounit 134 which terminates introduction of liquid into thetub 22.

Referring back to FIG. 6, it is seen that thereference curve 59 is a step curve having a firsthigher portion 59a between the increment values 4-8 and a second level lower portion 59b for theincrement 9 through the full level in thetub 22. This stepped curve shows reference values which when compared with the average of the last four flow pulse counts and the individual last four pulse count averages provides for a simplified yet accurate determination allowing for various component and clothes load variations to determine whether the liquid volume entering thetub 22 at the various liquid level increments has approached or equalled the experimentally determined values shown bycurve 57.

Since many loads are not totally displaced during the filling process and do not require enough water to totally displace them for proper washing, thereference curve 59 is selected to provide adequate liquid levels for various size loads.

As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a machine for liquid treatment of materials having a container for receiving the materials,

liquid control apparatus comprising sensing means for determining the volume of liquid added to the container which is required to increase the level of liquid within the container by specified increments, and

controller means controlled by said sensing means for determining from said volumes and increment levels the amount of liquid required in said container, said controller means introducing such required amount of liquid into said container.

2. In a machine for liquid treatment of materials having a container into which a batch of materials may be charged,

liquid control apparatus comprising,

liquid supply means for introducing liquid into said container including

means for determining the volume of liquid being introduced,

means for continuously determining the level of liquid within said container,

means for determining whether the level of liquid in said container is sufficient to cause full displacement of the liquid by the materials in said container, and

means for controlling said liquid supply means to terminate the introduction of liquid into the container when an optimum level is reached.

3. In a washing machine having pre-settable sequential control means for operating automatically through a program of washing and rinsing steps,

a tub,

means for introducing liquid into said tub,

means for measuring a volume of liquid as it is introduced into said tub,

means for measuring the level of liquid within said tub,

means for comparing the volume of liquid needed to increase said level of liquid within the tub by a specific increment with a reference volume, and

means for terminating the introduction of further liquid into said tub after it is determined that said needed volume of liquid is greater than said reference volume.

4. In a washing machine,

a tub,

a basket within said tub for receiving articles to be washed,

pre-settable sequential control means comprising means for introducing liquid into said tub and basket and including means for determining a plurality of volumes of liquid being introduced into said tub,

means for determining a plurality of levels of liquid within the tub,

means for determining from the volumes of liquid required to raise the levels of said liquid within said tub by specified increments the amount of liquid required to wash said articles, and

means for terminating the introduction of said liquid into said tub when said required amount is reached.

5. In an automatic washer,

pre-settable sequential control means for automatically regulating a machine through a programmed series of washing and rinsing steps comprising,

means for adding and measuring volumetrically a volume of liquid required to be added to a washer tub charged with material to be laundered to increase a liquid level in said tub by a predetermined increment,

means for averaging a plurality of said added volumes,

means for comparing such averaged measured volumes to a predetermined reference volume corresponding to a predetermined measured volume for an uncharged machine, and

means for terminating the addition of liquid automatically when the averaged measured volumes are greater than said reference volume a predetermined number of times, and thereafter continuing the preselected laundering program.

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